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Field-scale evaluation of the chemical–biological stabilization process for the remediation of hydrocarbon-contaminated soil
Adams, R.H.; Guzmán-Osorio, F.J. & Domínguez-Rodríguez, V.I.
Abstract
Developing countries face the challenge of
growing their economy while reducing the negative environmental
impacts of industry, thus requiring treatment
technologies that are economical and effective. One recent
technology developed in the tropical part of Mexico for the
remediation of petroleum-contaminated soil was tested in
this scale-up project at an industrial level, whereas previously
it had only been tested at laboratory scale; 150 m3 of
bentonitic mud, contaminated with weathered hydrocarbons
(3.4° API) at ~50,000 ppm, was treated with 4 %
Ca(OH)2, 4 % organic amendment, and a fine-root tropical
grass. Hydrocarbons in soil and in leachates, as well as pH,
and acute toxicity (Microtox) were monitored for
28.8 months. At the end of the study, basal respiration, root
density, and earthworm toxicity were also measured. The
hydrocarbon concentration in soil was reduced to 45 %,
and toxicity was eliminated. Hydrocarbons in leachates
were reduced to ~1 mg/l, safe for human consumption.
The pH adjustment depended on low soil moisture and was
stabilized at 7.1. Intense revegetation resulted in good root
density, within 90 % of nearby uncontaminated soil under
pasture. Basal respiration was increased to levels comparable
to uncontaminated tropical soils with agricultural use,
pasture and gallery forest. At an industrial scale, strict
moisture control was necessary for good pH stabilization.
By controlling these conditions and applying this novel
treatment process, it was possible to transform a heavily
contaminated geological material into a non-toxic, fertile,
soil-like substrate capable of maintaining a complete vegetative
cover and microbial activity comparable to similar
soils in a tropical environment.
Keywords
Appropriate technology; Leachates; Restoration; Total petroleum hydrocarbons; Tropics; Vegetative cover
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